Re: [2.4 PATCH] bugfix: ARP respond on all devices

On Tue, 19 Aug 2003 09:51:05 -0700
"David S. Miller" [off-list ref] wrote:

On Tue, 19 Aug 2003 17:54:26 +0100
Richard Underwood [off-list ref] wrote:

quoted

	When a HOST sends out an ARP request, it's NOT associated with a
single connection, it's associated with the host. Why should it pick a
"random" IP number to send as the source address?

It's not "random", it is using the IP address it intends
to use as the source in packets it will output once the
ARP completes.

In fact, if you look at the code in arp_solicit(), the source address
is coming directly from the packet we are trying to output.

Well, then you have a problem, at least with RFC-985 as quoted in my other
email.
If your host has two interfaces on two different pyhsical nets and host A from
net A shall be contacted by a service bound to your interface on net B you will
obviously send an arp request with a source ip from wrong subnet.
I did not read the code, I take your code explanation as true, of course.
It is very likely you will not receive a valid answer in this case:

<quote RFC-985>
An ARP request is discarded if the source IP address is not in the same subnet.
</quote>

Regards,
Stephan